The present invention relates to cleaning devices for use in electrophotographic apparatus or the like for removing the developer remaining on the surface of a photosensitive member after image transfer by scraping the developer off the surface, and more particularly to a cleaning device for removing the residual developer from the surface of an organic photosensitive member which is in rotation at a high peripheral speed of at least 26 cm/sec.
With conventional electrophotographic apparatus, the developer remaining on the surface of the photosensitive member after image transfer is removed generally by scraping off the developer from the surface of the photosensitive member with a cleaning blade held in pressing contact with the surface.
In addition to inorganic photosensitive members in which selenium, cadmium sulfide, amorphous silicon or the like is used, organic photosensitive members containing an organic photoconductive material have been introduced into wide use in recent years.
When the cleaning blade is used for removing the residual developer from the surface of the photosensitive member in high-speed systems wherein the member rotates at a high peripheral speed of at least 26 cm/sec, the cleaning blade often becomes raised off the surface of the photosensitive member owing to the vibration due to the high-speed rotation of the member, giving rise to the problem that the developer escapes through the clearance between the blade and the photosensitive member to produce image noises due to improper cleaning.
With the inorganic photosensitive member, improper cleaning can be remedied by pressing the cleaning blade against the member with an increased force or by using a cleaning blade made of a material of high restitution elasticity.
With the organic photosensitive member, however, the cleaning blade, when pressed on with a greater force, fails to slide on the photosensitive member smoothly and therefore becomes reversed to result in improper cleaning or impedes smooth rotation of the photosensitive member to necessitate an increased torque Furthermore, the organic photosensitive member, which is lower than the inorganic photosensitive member in hardness, has the problem that the increased force applied to the cleaning blade causes the blade to abrade the member to result in uneligible wear and markedly shortens the life of the member.
The surface wear of the organic photosensitive member can be diminished by forming a protective layer over the surface as is practiced in recent years, but the frictional contact of the cleaning blade with the member still remains unremedied Thus, the blade is likely to become reversed to entail improper cleaning or impede the rotation of the member.
Accordingly, in the case of electrophotographic apparatus wherein the photosensitive member is made of an organic material and rotated at a high peripheral speed of at least 26 cm/sec, there is a need to use a different cleaning device such as one having a fur brush for removing the residual developer from the surface of the member Another problem is then encountered in that the device is complex in construction and costly.